The present invention relates to a flyback transformer which supplies a high voltage to a cathode ray tube of a television receiver, specifically a flyback transformer having the secondary winding formed by winding a plurality of coil units into which the secondary winding is divided, around individual layer bobbins and assembling the layer bobbins in a plurality of layers.
The cathode ray tubes of television receivers require in general high DC voltages of 10 to 30 kV. This output voltage from the flyback transformer is rectified through rectifying diodes with high breakdown voltage strength.
In general, the flyback transformers are designed to generate high voltages by a higher harmonic tuning system, thus improving the regulation. Recently, for tuning at a higher frequency than the fifth harmonic, the secondary winding is divided into a plurality of coil units by a plurality of diodes to reduce a distributed capacitance of the secondary winding. In case of such secondary winding, each coil unit is separated to be alternatingly independent and therefore a pulse voltage generated by each coil unit is low and favorable for electrical insulation and a low breakdown voltage strength diode can be employed.
However, if the coil units are wound in layers with layer insulation paper or polyester film as conventional, the secondary winding increases in diameter and a leakage inductance necessarily increases and it is thus difficult to obtain higher harmonic tuning.
On the other hand, if the number of turns per layer of the coil unit is increased using the layer insulation paper or polyester film, a magnetic coupling to the primary winding increases and the leakage inductance becomes small but an insulation resin for insulation between layers is difficult to be impregnated into the layers and the insulation effect deteriorates accordingly from the point of view of dielectric strength.